The present invention relates to a brake slip-controlled hydraulic brake system for vehicles of the type including a brake master cylinder and at least one wheel brake which is connected to the brake master cylinder and a slip control device which senses wheel rotational behavior by means of a sensor and which, in response to the sensor signal, pursuant a defined algorithm, disconnects the hydraulic connection between the wheel brake and the master cylinder and/or establishes a hydraulic connection to a relief chamber.
A brake system of this type is described in U.S. application Ser. No. 944,242, now U.S. Pat. No. 4,750,790 filed Dec. 18, 1986, and corresponding to German printed patent application No. 35 45 236. A relief chamber in that system is confined by a floating piston guided in a cylinder, which piston, on the one hand, when pressure fluid enters from the brake, moves in opposition to the force of a weak spring for the purpose of increasing the relief chamber volume while, on the other hand, in the event that a pressure increase becomes necessary, the piston is displaced by a pneumatic drive for decreasing the relief chamber volume.
The control of the drive in this system is relatively complicated, since it must be ensured that, on the one hand, there is available sufficient drive power in the event that a pressure increase is required and, on the other hand, that the drive piston is retracted fast enough to enable sufficient pressure fluid relief to take place.
Also, the design of the cylinder incorporating the floating piston and the pneumatic drive in this system is structurally complex.